The geometry and dynamics of Danish anchor seine ropes on the seabed

We present a two-dimensional kinematic description of the geometry and dynamics of the ropes of demersal seines during deployment, towing, and hauling, using piriform curves. Piriforms (which means pear shaped) are relatively simple analytical curves, which we parameterize, using basic positional and operational data from typical Danish anchor seine hauls. We then demonstrate how we can estimate the area fished, and the speed, direction and angle of attack of any part of the seine net rope, at any time during the fishing process. This sort of information is fundamental to a better understanding of the capture process of demersal seines, their whole gear selectivity, and their environmental impact.